package www.qiyue.sm;

import java.util.ArrayList;
import java.util.Collections;
import java.util.List;
import java.util.concurrent.Callable;

public class MyCallable implements Callable {
    @Override
    public Object call() throws Exception {
        return null;
    }

    public static void main(String[] args) {
        ArrayList<String> strings = new ArrayList<>();
        List<String> list = Collections.synchronizedList(strings);
    }
}
